A Bahraini man accused of belonging to the Islamic State group speaks in Rmeilan in northeast Syria on February 13, 2018

Delil souleiman, AFP/File

With European public opinion hostile to repatriating homegrown jihadists, governments are not eager to reclaim radicalised citizens detained abroad.

"Denmark, Canada and Switzerland say they are ready to take women and children. But on condition that it's not done publicly," says Nadim Houry, director of terrorism and counter-terrorism for Human Rights Watch.

The watchdog estimates there are thousands of foreigners in Kurdish detention, including around 800 women and 1,200 children.

According to the Kurds, only Russia and Indonesia have agreed to take back their detainees, mostly women and children.

- Prisoners 'not priority' -

France insists any adults among the more than 40 French nationals held by Kurdish authorities should be tried where they are, so long as they face a "fair trial".

Among them is Thomas Barnouin, an alleged IS fighter who was captured in December by Syrian Kurdish forces.

The 36-year-old "was part of the most radical branch of IS", according to a source close to his case.

"Barnouin and several others are potential dangers and also mines of information on IS," the source adds.

Images provided by the Syrian Democratic Forces on February 10, 2018 show captured Britons El Shafee el-Sheikh (L) and Alexanda Amon Kotey (R) posing for mugshots in an undisclosed location

Handout, Syrian Democratic Forces/AFP/File

Kurdish forces also captured British citizens Alexanda Amon Kotey and El Shafee el-Sheikh, part of the infamous "Beatles" quartet accused of beheading around 20 hostages.

But Kurdish officials say they would rather pass off the foreigners to their own countries so they can focus on defending their territory from their arch-enemy Ankara.

"Our priority is not the prisoners -- it's Turkey," says Mahmud.

They feel betrayed after Western powers, namely the US, failed to halt a Turkish-led offensive on the Kurdish enclave of Afrin earlier this year.

"Why continue to keep foreign prisoners, particularly Western ones, if their countries don't support us against the Turks?" asks another local official.

Could the Kurds' frustration result in thousands of foreign jihadists being let loose?

"Our position remains to investigate and process these files, in cooperation with the authorities" of prisoners' home countries, says Khaled Issa, a Kurdish representative in France.

- Reconciliation rules -

The overwhelming number of both foreign and local suspects means that those that are tried do not get due process.

The accused appear directly in front of judges without a local lawyer or an appeals process.

If found guilty, they are generally sentenced to between five and seven years in prison, with the most extreme facing 20 years.

But HRW says the punishments are often reduced for good behaviour or by amnesties. Sentences can also be cut short if the accused belongs to an influential Syrian Arab tribe which acts as a guarantor, promising the ex-jihadist will stay on the right side of the law.

A Turkish man accused of collaborating with the Islamic State group speaks in Rmeilan in northeast Syria on February 13, 2018

Delil souleiman, AFP/File

"The Kurds have to manage a mosaic of different communities on their territory," says HRW's Houry.

The guiding principle, he says, is reconciliation: "We must all live together -- we therefore have no other choice."

Finding proof of active IS membership is difficult, especially when it comes to the hundreds of female suspects, who include women from Russia, Tunisia and Turkey.

While few have seen combat, some worked in police and religious units. Many married IS fighters and have two or three children, who are technically stateless.

"Last year, we judged 10 (Syrian women). We released half, the other half were sentenced to less than 10 years," says Kanaan.

The rulings are in stark contrast to those in the West, where sentences for terror-linked offences are only getting tougher.

As foreign fighters linger in detention, some have suggested using them as leverage.

"The Kurds can use this as a bargaining chip to get aid," says Fabrice Balanche, an academic expert on Syria.

But time may be running out.

A member of the US-backed Syrian Democratic Forces removes an Islamic State group flag in the town of Tabqa on April 30, 2017

DELIL SOULEIMAN, AFP/File

With the fight against IS ending, Kurds worry their US ally will abandon them -- a fear compounded by President Donald Trump's insistence on withdrawing from Syria.

"Without American support, the Kurds cannot hold back the Turks or another well-equipped army," says Balanche.

If the Kurdish administration in northern Syria subsequently collapses, what could happen to foreign prisoners?

Such questions were already being raised in the aftermath of Afrin's capture by Turkish-backed rebels.

While experts believe there were few, if any, foreign jihadists held in Kurdish-run prisons there, local jihadist detainees seem to have vanished without a trace, with Kurdish officials saying they have no knowledge of their fate.